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.......To make your heater last, install it with dielectric nipples or unions (if you have copper pipe)........

A much better idea is to use brass nipples and copper flex connectors with brass nuts.

The picture in my avatar is of the Houston Ship Channel and was taken from my backyard. I like to sit outside and slap mosquitos while watching countless supertankers, barges and cargo ships of every shape and size carry all sorts of deadly toxins to and fro. It's really beautiful at times.....just don't eat the three eyed fish....

Why is this a much better idea? Is it because the dielectric unions are more prone to leaking, or is there another reason that I haven't thought of?

How about using brass nipples, and then a brass union that is threaded on one side, and soldered to the copper on the other side, instead of the flex connector? Would that work?

Yes, of course it will. I like the flex connectors because they are easy and forgiving. The di-electric unions and nipples work but will eventually fail, you guessed it, to electrolysis. My plumbers replace them all over the hospital nearly everyday. Steel hot water tanks and brass nipples get along very well. Steel and anything else do not.

The picture in my avatar is of the Houston Ship Channel and was taken from my backyard. I like to sit outside and slap mosquitos while watching countless supertankers, barges and cargo ships of every shape and size carry all sorts of deadly toxins to and fro. It's really beautiful at times.....just don't eat the three eyed fish....

Why is this a much better idea? Is it because the dielectric unions are more prone to leaking, or is there another reason that I haven't thought of?

How about using brass nipples, and then a brass union that is threaded on one side, and soldered to the copper on the other side, instead of the flex connector? Would that work?

Copper flex connectors and dielectric unions work well because they have plastic inserts in them which serve as insulators. The inserts prevent contact between dissimilar metals. Copper flex connectors are easier to install, but they are thin and corrugated, so may be subject to earlier failure.

Uninsulated brass nipples and unions are not a good idea because you still have metal to metal contact. It doesn't matter which metal you use in between the steel and copper.

What matters is that you connect steel to steel and copper to copper (or brass), and that you have insulators between the steel tank and the copper pipe.

I don't what the feature of dielectric nipples is that makes them insulators.

According to this explanation, dielectric nipples work because they prevent water from coming in contact with the metals at their point of connection. The dielectric effect is enhanced by the water, which acts as an "electrolyte solution."

Uninsulated brass nipples and unions are not a good idea because you still have metal to metal contact. It doesn't matter which metal you use in between the steel and copper.

What matters is that you connect steel to steel and copper to copper (or brass), and that you have insulators between the steel tank and the copper pipe.

I don't think this is true. Brass can successfully be used as a type of dialectic buffer between steel and copper. I don't remember the exact specifics, but it has something to do with the nobility rating of the metals. Steel is on one end of the scale, copper is on the other end of the scale, and brass is about in the middle. Using enough brass in between the steel and copper will prevent electrolysis.

I don't think this is true. Brass can successfully be used as a type of dialectic buffer between steel and copper. I don't remember the exact specifics, but it has something to do with the nobility rating of the metals. Steel is on one end of the scale, copper is on the other end of the scale, and brass is about in the middle. Using enough brass in between the steel and copper will prevent electrolysis.

Many plumbers agree with you, but I haven't seen any data or science to support this belief. I did find these nuggets:

If dissimilar metals are used in a piping system, galvanic corrosion can occur even when no electrical devices are attached. The same principle that makes batteries work makes a battery out of a piping system with two different metals. Say you connect copper pipe to galvanized pipe. For battery/electrochemical reasons that it isn't really necessary to understand, electrons will try to flow from the copper pipe to the galvanized pipe. To balance the charges, this will cause some of the copper to dissolve into the water as positively charged ions, migrate through the water, and rejoin the electrons, and copper will deposit on the galvanized pipe. This copper came from the copper pipe, so it's a problem. If you install a dielectric union, it's just like turning off a switch on a battery operated system -- the electrons stop flowing. Dielectric unions are for the purpose of stopping these galvanic currents, and they work.

There is an old plumber''s tale that installing brass nipples in a steel tank is good, while putting copper fittings in steel is bad. If you look at the galvanic scale, you''ll see that copper and brass are side-by-side. Bronze, too. So, they all are going to force steel to rust. We''ve made that test. Galvanized steel screwed into brass will start rusting within days.

Stay with the 6 year warranty . A friend of mine told me that when he was in the plumbing bussiness they sold a 12year warranty water heater. The difference in the unit was that he would open the box and put a "12 year warranty" sticker on the side of the heater. That was the only difference. You paid more but got the same equipment. Through good engineering the six year unit usually lasts little more than 6 yrs. Just like a 5 year car battery. If you get over 5 years out of it you are LUCKY.